An example of a background art is disclosed in Patent literature 1. A scent generating apparatus disclosed in this Patent literature 1 pulsively injects a fragrance into the flowing air for infinitesimal time at short time intervals.
Furthermore, another example of the background art is disclosed in Patent literature 2. An olfactory display disclosed in this Patent literature 2 controls a concentration of a fragrance component by adjusting a mixing ratio of a fragrance and odorless air.
Patent literature 1: Japanese patent application laying-open No. 2009-82273 [A61M 21/02, A61L 9/02, A45D 34/02]
Patent literature 2: Japanese patent publication No. 5288573 [G09F 9/00, G09F 9/00, A61L 9/12]